In fixed word order languages like English, word order is highly predictive of a noun's thematic and grammatical role, and a large body of research has shown that speakers of fixed word order languages tend to rely on word order when they parse and interpret sentences. In flexible word order languages like Turkish, word order is less predictive of nouns' thematic and grammatical roles, and less is known about the types of cues adult speakers use to determine the meaning of sentences. How do speakers of free word order languages determine the grammatical role of nouns? To answer this question, we presented 28 adult speakers of Turkish 48 stimuli sentences where the word order was varied between SOV and OVS. The cues to aid the grammatical roles were word order, casemarking on the object noun, and when a casemarker was not present an indefinite determiner. The results suggest that, of the three morphosyntactic cues (word order, overt-casemarking, and determiner), word order is the primary cue that Turkish speakers use to assign grammatical and thematic roles, overt object casemarking is a strong secondary cue, and the indefinite determiner is a weaker tertiary cue.